Micromotors based e.g. on utilization of the piezoelectric effect are used in many different applications today. The motors have a typical size from a couple of millimeters to a couple of centimeters and are therefore very suitable for small size applications. The motors are typically driven utilizing an interaction between a rotor or shuttle and a driving element. The driving principle is in many applications based on ultrasonic resonances, but also driving principles based on walking, stepping, stick-slip mechanisms etc. are also commonly occurring. The drive elements are typically fixed against a motor housing, which typically in turn are fixed against a support on the device in which the created motion is to be provided. The rotor or shuttle is typically attached to a movable part of the device. This movable part is thus given a corresponding movement as the rotor or shuttle.
Small sizes of the part of the devices and small displacements of the movable parts put severe requirements on tolerances at mounting and operation. Even relatively small errors in dimensions and positions may severely influence the operation of the motor, since deflections and torsions between the shuttle/rotor and the driving elements strongly influence the interaction there between. Small errors in mounting precision may deform or even break bearings or other parts of the motor. As a result, a standard solution is to require extreme fine tolerances on many parts of the motor, which unfortunately results in high manufacturing costs and complex manufacturing procedures.
Moreover, the driving elements of electromechanical motors are driven by supplying different electrical signals to the active elements. Such electrical signals have to be supplied in some way, typically by an electrical connection, such as a cable. During mounting and operation, it is relatively common that such an electrical connection is exposed for external forces, and mechanical protective means for preventing any electrical contacts to be exposed to large mechanical forces have to be provided. However, such protective means in small sizes are difficult to provide and increase the manufacturing costs even further.
Mounting is typically the most costly part of the manufacturing of micromotors, and in particular the final mounting on the devices to be controlled. Precision for mounting and difficulties in cooperation with additional parts as e.g. sensors are well known areas of problems. All such problems typically sum up in expensive manufacturing of micromotors.